One of five is unaccountable (5)
I believe the answer is:
taste
'one' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for taste that I've seen before include "Test for flavour" , "Brief experience (of something)" , "Sample orally" , "Savour in the mouth" , "Little bit" .)